A five-year collaborative IRPG project is proposed in response to Program Announcement 94-054, "Strategies to Reduce HIV Sexual Risk Practices in Drug Users." The research program in Miami, Florida will focus on developing and implementing sexual risk-reduction interventions targeting injecting drug users and their sex partners not currently in drug treatment who are at increased risk of HIV infection/transmission as a consequence of their drug/sexual practices. The research study will be conducted in two phases. The first phase will consist of two sub-phases, 1A and 1B, which together will assess the individual, social, and environmental context of sexual risk behavior and sexual risk reduction, and inform the development of interventions to reduce sexual risk in targeted drug-user populations. Phase 1A will elicit in-depth qualitative information about behavioral and normative beliefs, barriers and facilitators, and social influence and network factors related to sexual risk reduction. In Phase 1B, a comprehensive interview instrument about specific risk-reducing sexual behaviors and their antecedents will be developed and administered, guided by data collected in Phase 1A. Additionally, a formalized behavioral context study of sexual risk-reducing behaviors will be conducted with injecting drug users and their sexual partners. Based on information gained in Phase 1, theory-driven, empirically informed interventions will be developed and evaluated in a randomized field experimental design for use during Phase 2. The Miami intervention is a sequenced and additive model in which three types of interventions will be compared: l) an individual counseling intervention , 2) a couple counseling intervention, and 3) a network-based intervention. Intervention strategies will be guided by the empirically derived framework of behavior change readiness. Randomization will provide the opportunity to measure the additive effects of dyad to individual counseling and of individual counseling + dyad counseling to network counseling. The three types of interventions will be sequenced in order to measure the separate effects of each intervention type. Although the stated research objectives will be substantially realized by the study design set forth in this proposal for Miami, FL, the value of the proposed initiative will be greatly enhanced by an expected collaboration with six other sites (Phoenix, Arizona; Houston, Texas; Long Beach, California; Miami, Florida; New Orleans, Louisiana; and Washington, D.C.) that propose to conduct independent complementary studies for development of sexual risk-reduction interventions within the same theoretical and analytical framework. Each collaborating site will develop unique interventions targeting local populations that will be compared with a standardized control intervention that is uniform across sites. Monitoring of sites (site visitors by the executive committee) will help ensure quality control for intervention integrity, and for data management and analyses.